Puerto Rico Highway 66 (unsigned Interstate PR3) is a main tollway which parallels Puerto Rico Highway 3 going from the city of Carolina, Puerto Rico via a 3 loops cloverleaf interchange with PR-26 and PR-3, a major exit in the form of a Trumpet interchange in Canóvanas, Puerto Rico and ending in the municipality of Río Grande, Puerto Rico with an intersection of PR-3. It is only 12.42 miles (19.99 km) long and has very few exits, which work mainly to minimize traffic in the congested Carolina area of PR-3.